Despite the large sites like Homeaway, TripKey and Stayz having verification procedures, the scams are still happening. Some scams are happening because of fictitious listings but the majority seem to be due to the hacking of the email enquiry. I do not know whether this is happening at the website end (Homeaway etc) , at the customer (renter) computer or at the property owner/manager computer.
It seems less likely that a major website would be hacked than the computer of the customer or owner. However, large organisations may have great web security but because they employ many people, they may be hacked from the inside.
Potential renters could take a few very simple steps to verify that a property exists and that the owner of that property is genuine:
Phone the owners and ask for their name and address. Check that name and address against the phone book listing (you can do this online or go to directory enquiries, give the operator the name and address and ask them to connect you).
Do a search using the listed property name and suburb of that property to see if it is listed on other websites or it may even have its own website. Check the phone numbers/email addresses are the same.
Where possible use the smaller local or regional sites to make a booking because they will usually be available on the phone and will know the owners and the properties. This also supports local Australian business rather than large multinational corporations.